零基础学python-14.2 python的文档资源：文档字符串

这一章节我们来说说文档字符串：__doc__

文档字符串其实也是注释的一种，但是它一般放在模块文件、函数或者类语句的顶部，主要用来说明它们是干什么的，为什么这样做

python会自动封装这些文字，放到__doc__属性里面

>>> def test():
	'这是一个测试方法'
	print('hello world')

>>> test.__doc__
'这是一个测试方法'
>>>

>>> class Test():
	'这是一个测试类'
	def helloworld():
		'测试方法'
		print('hello world')

		
>>> Test.helloworld ()
hello world
>>> Test.helloworld.__doc__
'测试方法'
>>> Test.__doc__
'这是一个测试类'
>>>

下面，我们再来说说内置文档字符串
python的内部已经提供了大量的文档给我们，我们导入模块的时候，只需要打印这个模块的__doc__属性，我们就可以大概知道这个模块是干什么的，还有方法列表等

>>> import sys
>>> print(sys.__doc__)
This module provides access to some objects used or maintained by the
interpreter and to functions that interact strongly with the interpreter.

Dynamic objects:

argv -- command line arguments; argv[0] is the script pathname if known
path -- module search path; path[0] is the script directory, else ''
modules -- dictionary of loaded modules

displayhook -- called to show results in an interactive session
excepthook -- called to handle any uncaught exception other than SystemExit
  To customize printing in an interactive session or to install a custom
  top-level exception handler, assign other functions to replace these.

stdin -- standard input file object; used by input()
stdout -- standard output file object; used by print()
stderr -- standard error object; used for error messages
  By assigning other file objects (or objects that behave like files)
  to these, it is possible to redirect all of the interpreter's I/O.

last_type -- type of last uncaught exception
last_value -- value of last uncaught exception
last_traceback -- traceback of last uncaught exception
  These three are only available in an interactive session after a
  traceback has been printed.

Static objects:

builtin_module_names -- tuple of module names built into this interpreter
copyright -- copyright notice pertaining to this interpreter
exec_prefix -- prefix used to find the machine-specific Python library
executable -- absolute path of the executable binary of the Python interpreter
float_info -- a struct sequence with information about the float implementation.
float_repr_style -- string indicating the style of repr() output for floats
hash_info -- a struct sequence with information about the hash algorithm.
hexversion -- version information encoded as a single integer
implementation -- Python implementation information.
int_info -- a struct sequence with information about the int implementation.
maxsize -- the largest supported length of containers.
maxunicode -- the value of the largest Unicode code point
platform -- platform identifier
prefix -- prefix used to find the Python library
thread_info -- a struct sequence with information about the thread implementation.
version -- the version of this interpreter as a string
version_info -- version information as a named tuple
dllhandle -- [Windows only] integer handle of the Python DLL
winver -- [Windows only] version number of the Python DLL
__stdin__ -- the original stdin; don't touch!
__stdout__ -- the original stdout; don't touch!
__stderr__ -- the original stderr; don't touch!
__displayhook__ -- the original displayhook; don't touch!
__excepthook__ -- the original excepthook; don't touch!

Functions:

displayhook() -- print an object to the screen, and save it in builtins._
excepthook() -- print an exception and its traceback to sys.stderr
exc_info() -- return thread-safe information about the current exception
exit() -- exit the interpreter by raising SystemExit
getdlopenflags() -- returns flags to be used for dlopen() calls
getprofile() -- get the global profiling function
getrefcount() -- return the reference count for an object (plus one :-)
getrecursionlimit() -- return the max recursion depth for the interpreter
getsizeof() -- return the size of an object in bytes
gettrace() -- get the global debug tracing function
setcheckinterval() -- control how often the interpreter checks for events
setdlopenflags() -- set the flags to be used for dlopen() calls
setprofile() -- set the global profiling function
setrecursionlimit() -- set the max recursion depth for the interpreter
settrace() -- set the global debug tracing function

>>>

总结，我们这一节主要描述了怎样使用文档字符串，以及简单讲述了内置文档字符串的使用

这一章节就说到这里，谢谢大家

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